Method and apparatus for transmitting data

ABSTRACT

Embodiments of the present disclosure provide a data transmission method and an apparatus. The method mainly includes: forming multiple antennas of a BS (base station) into a cross polarization antenna array, and calculating a weighted matrix of a to-be-transmitted data stream of the BS according to channel information between the BS and an MS (mobile station); performing weighted processing on the to-be-transmitted data stream of the BS according to the weighted matrix, and sending a data stream that has undergone the weighted processing from the BS to the MS. The embodiments of the present disclosure may enhance the demodulation performance because the cross polarization antenna array is adopted at the BS, and certain irrelevancy exists between cross antennas; therefore, the embodiments of the present disclosure may significantly enhance the overall performance of sending the data stream from a BS side to an MS side.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2011/073178, filed on Apr. 22, 2011, which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the field of communicationstechnologies, and in particular, to a method and apparatus fortransmitting data.

BACKGROUND

A BF (Beamforming, beamforming) weighting method adopts a multi-antennaarray, generates a corresponding weighted value by using channelinformation and weights transmit signals of multiple antennas, so as toenable the transmit signals of the multiple antennas to implementin-phase superposition and enhancement among one another when reachingthe receive end, just like that they are converged to the same beam.Therefore, a signal to noise ratio is increased and a multi-antennaarray gain and a certain diversity gain are obtained. The BF weightingmethod includes an EGT (Equal Gain Transmit, equal gain transmit)weighting method and an MRT (Maximum Ratio Transmit, maximum ratiotransmit) weighting method.

In a multi-antenna MIMO (Multi Input Multi Output, multi input multioutput) system, an MIMO A or MIMO B transmission format is separatelyadopted on two antennas to send a data stream at the same time.

In an actual application, an MIMO+BF technology is generally adopted toenhance the performance of dual stream transmission. At the transmitend, channel information is used to generate a corresponding weightedvalue, and the signal to noise ratio of the receive end is increased byusing weighting, so as to enhance the performance of MIMO.

A solution of transmitting a data stream by adopting the MIMO+BFtechnology in the prior art mainly includes that: a multi-antenna arrayof the transmit end adopts a vertical polarization antenna array. Acharacteristic of this antenna array is that channel relevancy betweenthe antennas is strong.

At least the following problems exist in the prior art:

When a data stream is transmitted by adopting the MIMO+BF technology, inorder to obtain the good diversity gain and demodulation performance inthe two transmission formats MIMO A and MIMO B, irrelevancy between theantennas needs to be used. However, in this method, because the channelrelevancy between the antennas is strong, the overall performance of theMIMO+BF technology is affected.

SUMMARY

Embodiments of the present disclosure provide a method and an apparatusfor transmitting data, to increase the overall performance for a BS(base station, base station) adopting a multi-antenna array to send adata stream to an MS (mobile station, mobile station).

A data transmission method, forming multiple antennas of a BS into across polarization antenna array, specifically includes:

-   calculating a weighted matrix of a to-be-transmitted data stream of    the BS according to channel information between the BS and an MS;    and-   performing weighted processing on the to-be-transmitted data stream    of the BS according to the weighted matrix, and sending a data    stream that has undergone the weighted processing from the BS to the    MS.

A data transmission apparatus includes:

-   a weighted matrix calculating module, configured to calculate a    weighted matrix of a to-be-transmitted data stream of a BS according    to channel information between the BS and an MS, where multiple    antennas of the BS form a cross polarization antenna array; and-   a weighted sending processing module, configured to perform weighted    processing on the to-be-transmitted data stream of the BS according    to the weighted matrix, and send a data stream that has undergone    the weighted processing from the BS to the MS.

It may be seen from the foregoing technical solutions provided by theembodiments of the present disclosure that, the embodiments of thepresent disclosure may enhance the demodulation performance because thecross polarization antenna array is adopted at the BS, and certainirrelevancy exists between cross antennas; therefore, the embodiments ofthe present disclosure may significantly enhance the overall performanceof sending the data stream from a BS side to an MS side.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic principle diagram of a data transmission method,which is based on an MIMO+BF technology using a cross polarizationantenna array and put forward by embodiment of the present disclosure;

FIG. 2 is a specific processing flowchart of a data transmission method,which is based on an MIMO+BF technology using a cross polarizationantenna array and put forward by embodiment of the present disclosure;and

FIG. 3 is a specific structural diagram of a data transmission apparatusaccording to an embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

The following describes embodiments of the present disclosure withreference to accompanying drawings.

In the embodiments of the present disclosure, multiple antennas of abase station BS form a cross polarization antenna array, and a weightedmatrix of a to-be-transmitted data stream of the BS is calculatedaccording to channel information between the BS and an MS. Then,weighted processing is performed on the to-be-transmitted data stream ofthe BS according to the weighted matrix, and a data stream that hasundergone the weighted processing is sent from the BS to the MS.

A schematic principle diagram of a data transmission method, which isbased on an MIMO+BF technology using a cross polarization antenna arrayand put forward by the embodiment, is shown in FIG. 1. A specificprocessing process includes the following processing steps, as shown inFIG. 2:

Step 21: Divide 2N antennas of a BS (base station, base station) intotwo groups, and form them into a cross polarization antenna array.

The multiple (2N) antennas of the BS are divided, and form the crosspolarization antenna array. A specific operation is that: the multipleantennas of the BS are divided into two groups according to apolarization direction, the polarization directions of the antennas ineach group are the same (i.e., polarization directions are parallel toeach other), and the polarization directions of the antennas between thetwo groups are perpendicular or orthogonal to each other, therebyforming the cross polarization antenna array.

In an actual application, the N may be any integer. For example, whenN=2, the BS has 4 transmit antennas, and an MS (mobile station, mobilestation) has 2 receive antennas, a channel response between a firstantenna of the BS and a first antenna of the MS is h₁₁, a channelresponse between a second antenna of the BS and the first antenna of theMS is h₁₂ , a channel response between a third antenna of the BS and thefirst antenna of the MS is h₁₃, and a channel response between a fourthantenna of the BS and the first antenna of the MS is h₁₄;

a channel response between the first antenna of the BS and a secondantenna of the MS is h₂₁, a channel response between the second antennaof the BS and the second antenna of the MS is h₂₂, a channel responsebetween the third antenna of the BS and the second antenna of the MS ish₂₃, and a channel response between the fourth antenna of the BS and thesecond antenna of the MS is h₂₄.

The first antenna and the third antenna of the BS are a first group, andthe second antenna and the fourth antenna of the BS are a second group.The polarization directions of the two antennas in the first group arethe same, and the polarization directions of the two antennas in thesecond group are the same. The polarization directions of the antennasbetween the first group and the second group are perpendicular ororthogonal to each other, that is, the polarization direction of the twoantennas in the first group and the polarization direction of the twoantennas in the second group are perpendicular or orthogonal to eachother.

The 8 channel responses may form a downlink channel response matrix:

$h = {\begin{bmatrix}h_{11} & h_{21} \\h_{12} & h_{22} \\h_{13} & h_{23} \\h_{14} & h_{24}\end{bmatrix} = \begin{bmatrix}h_{1} & h_{2}\end{bmatrix}}$

Step 22: Calculate a weighted matrix according to channel informationbetween the BS and the MS.

MIMO encoding is performed on to-be-transmitted data of the BS to obtaina data stream

${s = \begin{bmatrix}s_{1} \\s_{2}\end{bmatrix}},$

where the S₁ and the S₂ are two data streams.

The weighted matrix of the data stream s is calculated based on thechannel information, such as the channel responses between the antennasof the BS and the antennas of the MS.

$w = {\begin{bmatrix}w_{11} & w_{12} \\w_{21} & w_{22} \\w_{31} & w_{32} \\w_{41} & w_{42}\end{bmatrix}.}$

The w₁₁ is a weighted value corresponding to the S₁ data stream on thefirst antenna, the w₁₂ is a weighted value corresponding to the S₂ datastream on the first antenna, the w₂₁ is a weighted value correspondingto the S₁ data stream on the second antenna, the w₂₂ is a weighted valuecorresponding to the S₂ data stream on the second antenna, the w₃₁ is aweighted value corresponding to the S₁ data stream on the third antenna,the w₃₂ is a weighted value corresponding to the S₂ data stream on thethird antenna, the w₄₁ is a weighted value corresponding to the S₁ datastream on the fourth antenna, and the w₄₂ is a weighted valuecorresponding to the S₂ data stream on the fourth antenna.

When only one data stream of the two data streams is sent on eachantenna, for example, when only the S₁ data stream is sent on the firstantenna, the weighted value w₁₂ corresponding to the S₂ data stream onthe first antenna is 0; when only the S₂ data stream is sent on thesecond antenna, the weighted value w₂₁ corresponding to the S₁ datastream on the first antenna is 0; when only the S₁ data stream is senton the third antenna, the weighted value w₃₂ corresponding to the S₂data stream on the third antenna is 0; when only the S₂ data stream issent on the fourth antenna, the weighted value w₄₁ corresponding to theS₁ data stream on the fourth antenna is 0.

The weighted matrix may be written as:

$w = \begin{bmatrix}w_{11} & 0 \\0 & w_{22} \\w_{31} & 0 \\0 & w_{42}\end{bmatrix}$

Step 23: Perform weighted processing on the data stream according to theweighted matrix, and send a data stream that has undergone the weightedprocessing from the BS to the MS.

The weighted processing may be performed in a set weighting mode on thedata stream s according to the weighted matrix w to obtain ato-be-transmitted data stream w·s that has undergone the weightedprocessing. The adopted weighting mode may be an EGT (Equal GainTransmit, equal gain transmit) mode, or may be an MRT (Maximum RationTransmit, maximum ration transmit) mode.

The data stream w·s that has undergone the weighted processing istransmitted to the MS through each antenna of the BS corresponding tothe MS. On each antenna of the BS, the data stream w·s may be sent tothe MS.

The data stream received by the MS is Y=hws+N, where the N is a channelnoise.

The following embodiment provides multiple methods for calculating theweighted matrix w:

Method 1: A column vector of a channel response between each antenna ofthe BS and a certain antenna of the MS is h₁, then a first column vectorof the weighted matrix w is

${w_{1} = \frac{h_{1}^{*}}{h_{1}}},$

where the vector h₁* indicates a conjugate of h₁, and the ∥h₁∥ indicatesa modulus value of the vector h₁;

the second column vector W₂ of the weighted matrix w is an orthogonalvector of the first column vector W₁ ;

the weighted matrix w=[w₁, w₂].

For example, when the BS has 4 transmit antennas, the MS has 2 receiveantennas, and the column vector of the corresponding channel responsebetween each antenna of the BS and the certain antenna of the MS is

${h_{1} = \begin{bmatrix}h_{11} \\\begin{matrix}h_{12} \\h_{13} \\h_{14}\end{matrix}\end{bmatrix}},$

the first column vector of the weighted matrix w is

${w_{1} = \frac{h_{1}^{*}}{h_{1}}},$

where the h₁* indicates the conjugate of the vector h₁, and the ∥h₁∥indicates the modulus value of the vector h₁.

The second column vector w₂ of the weighted matrix w is an orthogonalvector of the first column vector. The

${w_{1} = \begin{bmatrix}w_{11} \\w_{21} \\w_{31} \\w_{41}\end{bmatrix}},$

the

${w_{2} = \begin{bmatrix}w_{12} \\w_{22} \\w_{32} \\w_{42}\end{bmatrix}},$

and the weighted matrix w=[w₁, w₂].

This method may also be applicable to a case where the BS has 2N (N isan integer, and N is greater than 2) transmit antennas, and the numberof receive antennas of the MS is greater than 2. In addition, thismethod is also applicable when the number of receive antennas of the MSis 1.

Method 2: When the BS has 4 transmit antennas, the channel responsebetween the first antenna of the BS and the first antenna of the MS ish₁₁, the channel response between the second antenna of the BS and thefirst antenna of the MS is h₁₂, the channel response between the thirdantenna of the BS and the first antenna of the MS is h₁₃, the channelresponse between the fourth antenna of the BS and the first antenna ofthe MS is h₁₄, where the first antenna and the third antenna are thefirst group, the second antenna and the fourth antenna are the secondgroup, the polarization directions of two antennas in each group are thesame, and the polarization directions of the antennas between the firstgroup and the second group are orthogonal to each other.

Then,

${r = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}}} \right)}},$

where k is an index of the channel responses, and N is a statistic sumof the channel responses;

the weighted matrix is

${w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}};$

where r* indicates a conjugate of r.

Method 3: Similar to the case in the method 2, when the BS has 4transmit antennas,

$r_{1} = {\sum\limits_{k = 1}^{N}\left( {{h_{11}(k)} \cdot {h_{13}^{*}(k)}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\left( {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} \right)}$

Where k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, and h₁₄*indicates a conjugate of h₁₄;

the weighted matrix is

${w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}};$

where r₁* indicates a conjugate of r₁, and r₂* indicates a conjugate ofr₂.

In the methods 2 and 3, the number of receive antennas of the MS isgenerally at least 2, but the methods are also applicable when thenumber of receive antennas of the MS is 1.

When a communications system learns a channel response matrix h(k)between each antenna of the BS and each antenna of the MS, the methodfor calculating the weighted matrix w(k) is as follows:

Method 1: SVD (Singular value decomposition, singular valuedecomposition) is performed on h(k) to obtain two singular vectors ofthe matrix h(k), and conjugates of the two singular vectors are used astwo column vectors of the weighted matrix w(k).

Method 2: The weighted matrix w(k)=h*(k), where h*(k) indicates aconjugate of h(k).

Method 3: A channel covariance matrix

$R = {\sum\limits_{k = 1}^{N}\left( {{h(k)} \cdot {h^{H}(k)}} \right)}$

is calculated, where k is an index of the channel responses, N is astatistic sum of the channel responses, and h^(H)(k) indicates aconjugate transpose of h(k). Eigenvalue decomposition is performed on Rto obtain two character vectors corresponding to a greatest eigenvalueand a second greatest eigenvalue of R. Conjugates of the two charactervectors are used as two column vectors of the weighted matrix w.

For example, in a specific embodiment, when the BS has 4 transmitantennas, and the MS has 2 receive antennas, the channel responsebetween the first antenna of the BS and the first antenna of the MS ish₁₁, the channel response between the second antenna of the BS and thefirst antenna of the MS is h₁₂, the channel response between the thirdantenna of the BS and the first antenna of the MS is h₁₃, the channelresponse between the fourth antenna of the BS and the first antenna ofthe MS is h₁₄ , where the first antenna and the third antenna of the BSare the first group, the second antenna and the fourth antenna of the BSare the second group, the polarization directions of two antennas ineach group are the same, and the polarization directions of the antennasbetween the first group and the second group are orthogonal to eachother;

the channel response between the first antenna of the BS and the secondantenna of the MS is h₂₁, the channel response between the secondantenna of the BS and the second antenna of the MS is h₂₂, the channelresponse between the third antenna of the BS and the second antenna ofthe MS is h₂₃, and the channel response between the fourth antenna ofthe BS and the second antenna of the MS is h₂₄;

when the communications system learns that the channel response matrixbetween each antenna of the BS and each antenna of the MS is

${h(k)} = {\begin{bmatrix}{h_{11}(k)} & {h_{21}(k)} \\{h_{12}(k)} & {h_{22}(k)} \\{h_{13}(k)} & {h_{23}(k)} \\{h_{14}(k)} & {h_{24}(k)}\end{bmatrix} = \left\lbrack \begin{matrix}{h_{1}(k)} & {\left. {h_{2}(k)} \right\rbrack,}\end{matrix} \right.}$

the methods for calculating the weighted matrix w include the following:

Method 1:

$r = {\sum\limits_{k = 1}^{N}\left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}$

where k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄.

The weighted matrix

$w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}$

where r* indicates a conjugate of r.

Method 2:

$r_{1} = {\sum\limits_{k = 1}^{N}\left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\left( {{{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}$

where k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄.

The weighted matrix

$w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}$

where r₁* indicates a conjugate of r₁, and r₂* indicates a conjugate ofr₂.

In a Wimax TDD system, as a data transmission method based on an MIMO+BFtechnology using a cross polarization antenna array in embodiments ofthe present disclosure is adopted, MIMO transmission performance hasabout 15 dB gain compared with a case where a multi-antenna array is avertical polarization antenna array.

Based on the data transmission method, an embodiment of the presentdisclosure further provides a data transmission apparatus, and aspecific structure includes the following processing modules, as shownin FIG. 3:

a weighted matrix calculating module 31, configured to calculate aweighted matrix of a to-be-transmitted data stream of a BS according tochannel information between the BS and an MS, where multiple antennas ofthe BS form a cross polarization antenna array;

where the multiple (2N) antennas of the BS are divided, and form thecross polarization antenna array; a specific operation is that: themultiple antennas of the BS are divided into two groups according to apolarization direction, the polarization directions of the antennas ineach group are the same, and the polarization directions of the antennasbetween the two groups are orthogonal to each other, thereby forming thecross polarization antenna array; and

a weighted sending processing module 32, configured to perform weightedprocessing on the to-be-transmitted data stream of the BS according tothe weighted matrix, and send a data stream that has undergone theweighted processing from the BS to the MS.

The weighted matrix calculating module 31 specifically includes at leastone of a first calculating module 311, a second calculating module 312,a third calculating module 313, and a fourth calculating module 314.

The first calculating module 311 is configured to, when a column vectorof a channel response between each antenna of the BS and a certainantenna of the MS is h₁, obtain a first column vector

$w_{1} = \frac{h_{1}^{*}}{h_{1}}$

of the weighted matrix w, where the vector h₁* indicates a conjugate ofh₁, and ∥h₁∥ indicates a modulus value of the vector h₁;

obtain a second column vector W₂, which is an orthogonal vector of thefirst column vector W₁ , of the weighted matrix w;

the weighted matrix w=[w₁, w₂].

For example, when the BS has 4 transmit antennas, the MS has 2 receiveantennas, and the column vector of the corresponding channel responsebetween each antenna of the BS and the certain antenna of the MS is

${h_{1} = \begin{bmatrix}h_{11} \\h_{12} \\h_{13} \\h_{14}\end{bmatrix}},$

the first column vector of the weighted matrix w is

${w_{1} = \frac{h_{1}^{*}}{h_{1}}},$

where h₁* indicates the conjugate of the vector h₁, and ∥h₁∥ indicatesthe modulus value of the vector h₁.

The second column vector w₂ of the weighted matrix w is an orthogonalvector of the first column vector

${w_{1} = \begin{bmatrix}w_{11} \\w_{21} \\w_{31} \\w_{41}\end{bmatrix}},{w_{2} = \begin{bmatrix}w_{12} \\w_{22} \\w_{32} \\w_{42}\end{bmatrix}},$

and the weighted matrix w=[w₁, w₂].

This method may also be applicable to a case where the BS has 2N (N isan integer, and N is greater than 2) transmit antennas.

The second calculating module 312 is configured to, when the BS has 4transmit antennas, obtain a channel response h₁₁ between a first antennaof the BS and a first antenna of the MS, a channel response h₁₂ betweena second antenna of the BS and the first antenna of the MS, a channelresponse h₁₃ between a third antenna of the BS and the first antenna ofthe MS, a channel response h₁₄ between a fourth antenna of the BS andthe first antenna of the MS, where the first antenna and the thirdantenna of the BS are a first group, the second antenna and the fourthantenna of the BS are a second group, polarization directions of twoantennas in each group are the same, and the polarization directions ofthe antennas between the first group and the second group are orthogonalto each other;

${r = {\sum\limits_{k = 1}^{N}\left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}}} \right)}},$

where k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, and h₁₄*indicates a conjugate of h₁₄,

the weighted matrix

$w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}$

where r* indicates a conjugate of r;

or;

$r_{1} = {\sum\limits_{k = 1}^{N}\; \left( {{h_{11}(k)} \cdot {h_{13}^{*}(k)}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\; \left( {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} \right)}$

where k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, and h₁₄*indicates a conjugate of h₁₄,

the weighted matrix

$w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}$

where r₁* indicates a conjugate of r₁, and r₂* indicates a conjugate ofr₂.

The third calculating module 313 is configured to, when a channelresponse matrix between each antenna of the BS and each antenna of theMS is h(k), obtain the weighted matrix w(k)=h*(k), where h*(k) indicatesa conjugate of h(k);

or, perform singular value decomposition on h(k) to obtain a first and asecond singular vectors of the matrix h(k), and use conjugates of thetwo singular vectors as two column vectors of the weighted matrix w(k);

or, calculate a channel covariance matrix

${R = {\sum\limits_{k = 1}^{N}\left( {{h(k)} \cdot {h^{H}(k)}} \right)}},$

where k is an index of the channel responses, N is a statistic sum ofthe channel responses, and h^(H)(k) indicates a conjugate transpose ofh(k), perform eigenvalue decomposition on R to obtain two charactervectors corresponding to a greatest eigenvalue and a second greatesteigenvalue of R, and use conjugates of the two character vectors as twocolumn vectors of the weighted matrix w.

The fourth calculating module 314 is configured to, when the BS has 4transmit antennas, and the MS has 2 receive antennas, obtain a channelresponse h₁₁, between a first antenna of the BS and a first antenna ofthe MS a channel response h₁₂ between a second antenna of the BS and thefirst antenna of the MS, a channel response h₁₃ between a third antennaof the BS and the first antenna of the MS, a channel response h₁₄between a fourth antenna of the BS and the first antenna of the MS,where the first antenna and the third antenna of the BS are a firstgroup, the second antenna and the fourth antenna of the BS are a secondgroup, polarization directions of two antennas in each group are thesame, and the polarization directions of the antennas between the firstgroup and the second group are orthogonal to each other;

a channel response between the first antenna of the BS and a secondantenna of the MS is h₂₁, a channel response between the second antennaof the BS and the second antenna of the MS is h₂₂, a channel responsebetween the third antenna of the BS and the second antenna of the MS ish₂₃, and a channel response between the fourth antenna of the BS and thesecond antenna of the MS is h₂₄;

${r = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}},$

where k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄,

the weighted matrix

$w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}$

where r* indicates a conjugate of r;

or,

$r_{1} = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}$

where k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄,

the weighted matrix

$w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}$

where r₁* indicates a conjugate of r₁, and r₂* indicates a conjugate ofr₂.

The weighted sending processing module 32 includes:

a weighted processing module 321, configured to perform multi inputmulti output MIMO encoding on to-be-transmitted data of a BS to obtain adata stream

${s = \begin{bmatrix}s_{1} \\s_{2}\end{bmatrix}},$

where S₁ and S₂ are two data streams; and perform weighted processing onthe data stream s according to the weighted matrix w to obtain a datastream w·s that has undergone the weighted processing; and

a sending processing module 322, configured to transmit the data streamw·s that has undergone the weighted processing to the MS through eachantenna of the BS corresponding to the MS.

The foregoing apparatus may specifically be the base station BS, or aspecific module integrated in the BS.

To sum up, embodiments of the present disclosure may enhance thedemodulation performance of MIMO demodulation because a crosspolarization antenna array is adopted at a BS and certain irrelevancyexists between cross antennas, which is beneficial to the MIMOdemodulation. In addition, an array gain of BF may be enhanced becausethe cross polarization antenna array has a co-polarization antenna groupand certain relevancy exists between co-polarization antennas, which isalso beneficial to the BF. Therefore, the embodiments of the presentdisclosure, by combining the cross polarization antenna array and anMIMO+BF technology, decrease the number of conditions of an MIMOequivalent channel in the MIMO+BF technology, and significantly enhancethe overall performance of a communications system adopting the MIMO+BFtechnology.

The embodiments of the present disclosure calculate a weighted matrixaccording to the channel information between the BS and an MS. A methodfor calculating the weighted matrix is flexible, capable of performingadaptive adjustment to adapt to a channel change.

In the embodiments of the present disclosure, beam forming may beperformed in a case of multiple antennas to make signals implementin-phase superposition, and also make relevancy of the antennas decreaseto be beneficial to the MIMO demodulation. In the embodiments of thepresent disclosure, after a cross polarization antenna is adopted,energy of each character vector is approximately the same, which isbeneficial to dual stream transmission.

Through description of the foregoing embodiments, a person skilled inthe art may clearly understand that the present disclosure may beimplemented by hardware, and may also be implemented by software plus anecessary hardware platform. For example, the various “modules”described herein may be implemented in one or more processors (e.g.,each module may implemented in a separate processor or multiple modulesmay be implemented in a single processor) resident in computer equipment(e.g., a personal computer, a server, a network device, and so on).Based on such an understanding, a technical solution of the presentdisclosure may be implemented in a form of a software product. Thesoftware product may be stored on a non-transitory computer readablestorage medium (e.g., a CD-ROM, a USB drive, a mobile hard disk, and soon), and includes several instructions to make a computer equipment(e.g., a personal computer, a server, or a network device, and so on) toexecute the method described in each embodiment of the presentdisclosure.

The foregoing descriptions are merely exemplary specific embodiments ofthe present disclosure, but are not intended to limit the protectionscope of the present disclosure.

Any variation or replacement readily figured out by a person skilled inthe art within the technical scope disclosed in the present disclosureshall fall within the protection scope of the present disclosure.Therefore, the protection scope of the present disclosure shall besubject to the protection scope of the claims.

What is claimed is:
 1. A data transmission method, wherein multipleantennas of a base station (BS) form a cross polarization antenna array,the method comprising: calculating a weighted matrix of ato-be-transmitted data stream of the BS according to channel informationbetween the BS and a mobile station (MS); and performing weightedprocessing on the to-be-transmitted data stream of the BS according tothe weighted matrix, and sending a data stream that has undergone theweighted processing from the BS to the MS.
 2. The data transmissionmethod according to claim 1, further including forming the crosspolarization antenna array by dividing the multiple antennas of the BSinto two groups according to a polarization direction, whereinpolarization directions of the antennas in each group are the same, andpolarization directions of the antennas between the two groups areorthogonal to each other.
 3. The data transmission method according toclaim 1, wherein the calculating a weighted matrix of ato-be-transmitted data stream of the BS according to channel informationbetween the BS and the MS comprises: obtaining a column vector h₁ of achannel response between each antenna of the BS and a certain antenna ofthe MS, and then a first column vector$w_{1} = \frac{h_{1}^{*}}{h_{1}}$ of the weighted matrix w, whereinthe vector h₁* indicates a conjugate of h₁, and ∥h₁∥ indicates a modulusvalue of the vector h₁; and obtaining a second column vector W₂, whichis an orthogonal vector of the first column vector W₁, of the weightedmatrix w; wherein the weighted matrix w=[w₁, w₂].
 4. The datatransmission method according to claim 1, wherein the calculating aweighted matrix of a to-be-transmitted data stream of the BS accordingto channel information between the BS and the MS comprises: when the BShas 4 transmit antennas, obtaining a channel response h₁₁ between afirst antenna of the BS and a first antenna of the MS, a channelresponse h₁₂ between a second antenna of the BS and the first antenna ofthe MS, a channel response h₁₃ between a third antenna of the BS and thefirst antenna of the MS, a channel response h₁₄ between a fourth antennaof the BS and the first antenna of the MS, wherein the first antenna andthe third antenna are a first group, the second antenna and the fourthantenna are a second group, wherein polarization directions of twoantennas in each group are the same, and wherein polarization directionsof the antennas between the first group and the second group areorthogonal to each other; wherein${r = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}}} \right)}},$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, and h₁₄*indicates a conjugate of h₁₄; the weighted matrix ${w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}};$ wherein r* indicates a conjugate of r; or;$r_{1} = {\sum\limits_{k = 1}^{N}\; \left( {{h_{11}(k)} \cdot {h_{13}^{*}(k)}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\; \left( {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} \right)}$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, and h₁₄*indicates a conjugate of h₁₄; the weighted matrix ${w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}};$ and wherein r₁* indicates a conjugate of r₁, and r₂*indicates a conjugate of r₂.
 5. The data transmission method accordingto claim 1, wherein the calculating a weighted matrix of ato-be-transmitted data stream of the BS according to channel informationbetween the BS and the MS comprises: when a channel response matrixbetween each antenna of the BS and each antenna of the MS is h(k),obtaining the weighted matrix w(k)=h*(k), wherein h*(k) indicates aconjugate of h(k); or, performing singular value decomposition on h(k)to obtain a first singular vector and a second singular vector of thematrix h(k), and using conjugates of the first and second singularvectors as two column vectors of the weighted matrix w(k); or,calculating a channel covariance matrix${R = {\sum\limits_{k = 1}^{N}\; \left( {{h(k)} \cdot {h^{H}(k)}} \right)}},$wherein k is an index of channel responses, N is a statistic sum of thechannel responses, and h^(H)(k) indicates a conjugate transpose of h(k),performing eigenvalue decomposition on R to obtain two character vectorscorresponding to a greatest eigenvalue and a second greatest eigenvalueof R, and using conjugates of the two character vectors as two columnvectors of the weighted matrix w.
 6. The data transmission methodaccording to claim 1, wherein the calculating a weighted matrix of ato-be-transmitted data stream of the BS according to channel informationbetween the BS and the MS comprises: when the BS has 4 transmitantennas, and the MS has 2 receive antennas, obtaining a channelresponse h₁₁ between a first antenna of the BS and a first antenna ofthe MS, a channel response h₁₂ between a second antenna of the BS andthe first antenna of the MS, a channel response h₁₃ between a thirdantenna of the BS and the first antenna of the MS, a channel responseh₁₄ between a fourth antenna of the BS and the first antenna of the MS,wherein the first antenna and the third antenna of the BS are a firstgroup, the second antenna and the fourth antenna of the BS are a secondgroup, wherein polarization directions of two antennas in each group arethe same, and wherein polarization directions of the antennas betweenthe first group and the second group are orthogonal to each other;obtaining a channel response h₂₁ between the first antenna of the BS anda second antenna of the MS, a channel response h₂₂ between the secondantenna of the BS and the second antenna of the MS, a channel responseh₂₃ between the third antenna of the BS and the second antenna of theMS, and the channel response h₂₄ between the fourth antenna of the BSand the second antenna of the MS; wherein${r = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}},$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄; the weighted matrix $w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}$ wherein r* indicates a conjugate of r; or,$r_{1} = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄; the weighted matrix $w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}$ and wherein r₁* indicates a conjugate of r₁, and r₂*indicates a conjugate of r₂.
 7. The data transmission method accordingto claim 1, wherein the performing weighted processing on theto-be-transmitted data stream of the BS according to the weightedmatrix, and sending a data stream that has undergone the weightedprocessing from the BS to the MS comprises: performing multi input multioutput MIMO encoding on the to-be-transmitted data stream of the BS toobtain a data stream ${s = \begin{bmatrix}s_{1} \\s_{2}\end{bmatrix}},$ wherein S₁ and S₂ are two data streams; performing theweighted processing on the data stream s according to the weightedmatrix w to obtain a data stream w·s that has undergone the weightedprocessing; and transmitting the data stream w·s that has undergone theweighted processing to the MS through each antenna of the BScorresponding to the MS.
 8. A data transmission apparatus, comprising: aweighted matrix calculating module that calculates a weighted matrix ofa to-be-transmitted data stream of a base station (BS) according tochannel information between the BS and a mobile station (MS), whereinmultiple antennas of the BS form a cross polarization antenna array; anda weighted sending processing module that performs weighted processingon the to-be-transmitted data stream of the BS according to the weightedmatrix, and sends a data stream that has undergone the weightedprocessing from the BS to the MS.
 9. The data transmission apparatusaccording to claim 8, wherein the weighted matrix calculating modulecomprises at least one of a first calculating module, a secondcalculating module, a third calculating module, and a fourth calculatingmodule; wherein the first calculating module is configured to, when acolumn vector of a channel response between each antenna of the BS and acertain antenna of the MS is h₁, obtain a first column vector$w_{1} = \frac{h_{1}^{*}}{h_{1}}$ of the weighted matrix w, whereinthe vector h₁* indicates a conjugate of h₁, and the ∥h₁∥ indicates amodulus value of the vector h₁; obtain a second column vector W₂, whichis an orthogonal vector of the first column vector W₁, of the weightedmatrix w; the weighted matrix w=[w₁, w₂]; wherein the second calculatingmodule is configured to, when the BS has 4 transmit antennas, obtain achannel response h₁₁ between a first antenna of the BS and a firstantenna of the MS, a channel response h₁₂ between a second antenna ofthe BS and the first antenna of the MS, a channel response h₁₃ between athird antenna of the BS and the first antenna of the MS, a channelresponse h₁₄ between a fourth antenna of the BS and the first antenna ofthe MS, wherein the first antenna and the third antenna of the BS are afirst group, the second antenna and the fourth antenna of the BS are asecond group, wherein polarization directions of two antennas in eachgroup are the same, and wherein polarization directions of the antennasbetween the first group and the second group are orthogonal to eachother; wherein${r = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}}} \right)}},$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, and h₁₄*indicates a conjugate of h₁₄; the weighted matrix $w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}$ wherein r* indicates a conjugate of r; or;$r_{1} = {\sum\limits_{k = 1}^{N}\; \left( {{h_{11}(k)} \cdot {h_{13}^{*}(k)}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\; \left( {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} \right)}$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, and h₁₄*indicates a conjugate of h₁₄; the weighted matrix $w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}$ wherein r₁* indicates a conjugate of r₁, and r₂*indicates a conjugate of r₂; wherein the third calculating module isconfigured to, when a channel response matrix between each antenna ofthe BS and each antenna of the MS is h(k), obtain the weighted matrixw(k)=h*(k), wherein the h*(k) indicates a conjugate of h(k); or, performsingular value decomposition on h(k) to obtain a first singular vectorand a second singular vector of the matrix h(k), and use conjugates ofthe first and second singular vectors as two column vectors of theweighted matrix w(k); or, calculate a channel covariance matrix${R = {\sum\limits_{k = 1}^{N}\; \left( {{h(k)} \cdot {h^{H}(k)}} \right)}},$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, and h^(H)(k) indicates a conjugate transpose ofh(k), perform eigenvalue decomposition on R to obtain two charactervectors corresponding to a greatest eigenvalue and a second greatesteigenvalue of R, and use conjugates of the two character vectors as twocolumn vectors of the weighted matrix w; wherein the fourth calculatingmodule is configured to, when the BS has 4 transmit antennas, and the MShas 2 receive antennas, obtain a channel response h₁₁ between a firstantenna of the BS and a first antenna of the MS, a channel response h₁₂between a second antenna of the BS and the first antenna of the MS, achannel response h₁₃ between a third antenna of the BS and the firstantenna of the MS, a channel response h₁₄ between a fourth antenna ofthe BS and the first antenna of the MS, wherein the first antenna andthe third antenna of the BS are a first group, the second antenna andthe fourth antenna of the BS are a second group, wherein polarizationdirections of two antennas in each group are the same, and whereinpolarization directions of the antennas between the first group and thesecond group are orthogonal to each other; wherein a channel responsebetween the first antenna of the BS and a second antenna of the MS ish₂₁, a channel response between the second antenna of the BS and thesecond antenna of the MS is h₂₂, a channel response between the thirdantenna of the BS and the second antenna of the MS is h₂₃, and a channelresponse between the fourth antenna of the BS and the second antenna ofthe MS is h₂₄;${r = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}},$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄, the weighted matrix $w = \begin{bmatrix}\frac{r^{*}}{r} & 0 \\0 & \frac{r^{*}}{r} \\1 & 0 \\0 & 1\end{bmatrix}$ wherein r* indicates a conjugate of r; or,$r_{1} = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{11}(k)} \cdot {h_{13}^{*}(k)}} + {{h_{21}(k)} \cdot {h_{23}^{*}(k)}}} \right)}$$r_{2} = {\sum\limits_{k = 1}^{N}\; \left( {{{h_{12}(k)} \cdot {h_{14}^{*}(k)}} + {{h_{22}(k)} \cdot {h_{24}^{*}(k)}}} \right)}$wherein k is an index of the channel responses, N is a statistic sum ofthe channel responses, h₁₃* indicates a conjugate of h₁₃, h₁₄* indicatesa conjugate of h₁₄, h₂₃* indicates a conjugate of h₂₃, and h₂₄*indicates a conjugate of h₂₄; the weighted matrix $w = \begin{bmatrix}\frac{r_{1}^{*}}{r_{1}} & 0 \\0 & \frac{r_{2}^{*}}{r_{2}} \\1 & 0 \\0 & 1\end{bmatrix}$ and wherein r₁* indicates a conjugate of r₁, and r₂*indicates a conjugate of r₂.
 10. The data transmission apparatusaccording to claim 8, wherein the weighted sending processing modulecomprises: a weighted processing module, configured to perform multiinput multi output MIMO encoding on to-be-transmitted data of the BS toobtain a data stream ${s = \begin{bmatrix}s_{1} \\s_{2}\end{bmatrix}},$ wherein S₁ and S₂ are two data streams; and perform theweighted processing on the data stream s according to the weightedmatrix w to obtain a data stream w·s that has undergone the weightedprocessing; and a sending processing module, configured to transmit thedata stream w·s that has undergone the weighted processing to the MSthrough each antenna of the BS corresponding to the MS.